Biomedical subjects

M S Kindy

Publications and source records attributed to M S Kindy.

At least 37 records · Page 2Linked to original sources

PubMed1998

In vitro amyloid fibril formation by synthetic peptides corresponding to the amino terminus of apoSAA isoforms from amyloid-susceptible and amyloid-resistant mice.

Specific proteins of the apolipoprotein serum amyloid (apoSAA) family that are synthesized in large quantities during the acute, early phase of inflammation can serve as the proteinaceous precursors for amyloid fibrils. To model fibrillogenesis in such inflammatory diseases, we have used electron microscopy and X-ray diffraction to examine the structures formed by synthetic peptides corresponding in sequence to the 11 amino-terminal amino acids of murine apoSAA1, apoSAAcej, and apoSAA2 and to the 15 amino-terminal amino acids of apoSAA2. This region is reported to be the major fibrillogenic determinant of apoSAA isoforms. Both in 1 mM Tris buffer and in 35% acetonitrile, 0.1% trifluoracetic acid (ACN/TFA), all of the peptides formed macromolecular assemblies consisting of twisted, approximately 40- to 60-A-thick ribbons, which varied in width from around 40-70 A (for 11-mer apoSAA2 in Tris) up to 900 A (for the other peptides). X-ray diffraction patterns recorded from lyophilized peptides, vapor-hydrated samples, and solubilized/dried samples showed hydrogen bonding and intersheet reflections typical of a beta-pleated sheet conformation. The coherent lengths measured from the breadths of the X-ray reflections indicated that with hydration the growth of the assemblies in the intersheet stacking direction was comparable to that in the hydrogen-bonding direction, and analysis of oriented samples showed that the beta-strands were oriented perpendicular to both the long axis and the face of the assemblies. These X-ray results are consistent with the ribbon- or plate-like morphology of the individual aggregates and emphasize the polymorphic nature of amyloidogenic peptides. Our findings demonstrate that X-ray diffraction measurements on vapor-hydrated or solubilized/dried versus lyophilized, amyloidogenic peptides are a good indicator of their fibrillogenic potential. For example, from the highest to the lowest potential, the peptides examined here were ranked as: Abeta1-28 > Abeta1-40 > apoSAA1 approximately apoSAAcej > apoSAA2 > Abeta17-42. Experiments in which the three different 11-mer apoSAA isoforms were solubilized in ACN/TFA and then combined as binary mixtures showed that the ribbon morphology was not affected but that the extent of hydrogen bonding in the assemblies was substantially reduced. Our observations on the in vitro assembly of apoSAA analogs emphasize that amyloid fibril formation and morphology depend on primary sequence, length of polypeptide chain, the presence of additional fibrillogenic polypeptides, and solvent conditions.

Amino Acid Sequence↗

PubMed1998

Effect of nicotine use and withdrawal on brain preproenkephalin A mRNA.

Although the effect of nicotine on brain neurotransmitters and behavior has been studied, the mechanism(s) by which nicotine contributes to tobacco use remains unclear. One transmitter that may relate to long-term nicotine use and its withdrawal is enkephalin, a five-amino acid opioid peptide derived from the proenkephalin A family. In the present study we determined the effect of acute and chronic nicotine treatment and its withdrawal on preproenkephalin A mRNA levels (PPE mRNA) in specific rat brain regions using Northern blot analysis. Acute treatment with nicotine produced a significant increase in PPE mRNA in striatum and hippocampus. Chronic treatment with nicotine caused a significant decrease in PPE mRNA in these brain regions. In both striatum and hippocampus there was a rebound increase in PPE mRNA 24 h after nicotine cessation which approached the saline level 7 days later. Nicotine withdrawal 24 h following nicotine cessation, caused a significant increase in PPE mRNA in both brain regions. These effects of nicotine were blocked by pretreating rats with the nicotinic antagonist, mecamylamine. These data strongly suggest that brain opioid system(s) are involved in mediating nicotinic responses and its withdrawal and may have clinical implications in treating nicotine addiction.

Animals↗

PubMed1998

Adenoviral expression of murine serum amyloid A proteins to study amyloid fibrillogenesis.

Serum amyloid A (SAA) proteins are one of the most inducible acute-phase reactants and are precursors of secondary amyloidosis. In the mouse, SAA1 and SAA2 are induced in approximately equal quantities in response to amyloid induction models. These two isotypes differ in only 9 of 103 amino acid residues; however, only SAA2 is selectively deposited into amyloid fibrils. SAA expression in the CE/J mouse species is an exception in that gene duplication did not occur and the CE/J variant is a hybrid molecule sharing features of SAA1 and SAA2. However, even though it is more closely related to SAA2 it is not deposited as amyloid fibrils. We have developed an adenoviral vector system to overexpress SAA proteins in cell culture to determine the ability of these proteins to form amyloid fibrils, and to study the structural features in relation to amyloid formation. Both the SAA2 and CE/J SAA proteins were synthesized in large quantities and purified to homogeneity. Electron microscopic analysis of the SAA proteins revealed that the SAA2 protein was capable of forming amyloid fibrils, whereas the CE/J SAA was incapable. Radiolabelled SAAs were associated with normal or acute-phase high-density lipoproteins (HDLs); we examined them for their clearance from the circulation. In normal mice, SAA2 had a half-life of 70 min and CE/J SAA had a half-life of 120 min; however, in amyloid mice 50% of the SAA2 cleared in 55 min, compared with 135 min for the CE/J protein. When the SAA proteins were associated with acute-phase HDLs, SAA2 clearance was decreased to 60 min in normal mice compared with 30 min in amyloidogenic mice. Both normal and acute-phase HDLs were capable of depositing SAA2 into preformed amyloid fibrils, whereas the CE/J protein did not become associated with amyloid fibrils. This established approach opens the doors for large-scale SAA production and for the examination of specific amino acids involved in the fibrillogenic capability of the SAA2 molecule in vitro and in vivo.

Acute-Phase Proteins↗

PubMed1998

Mitochondrial manganese superoxide dismutase prevents neural apoptosis and reduces ischemic brain injury: suppression of peroxynitrite production, lipid peroxidation, and mitochondrial dysfunction.

Oxidative stress is implicated in neuronal apoptosis that occurs in physiological settings and in neurodegenerative disorders. Superoxide anion radical, produced during mitochondrial respiration, is involved in the generation of several potentially damaging reactive oxygen species including peroxynitrite. To examine directly the role of superoxide and peroxynitrite in neuronal apoptosis, we generated neural cell lines and transgenic mice that overexpress human mitochondrial manganese superoxide dismutase (MnSOD). In cultured pheochromocytoma PC6 cells, overexpression of mitochondria-localized MnSOD prevented apoptosis induced by Fe2+, amyloid beta-peptide (Abeta), and nitric oxide-generating agents. Accumulations of peroxynitrite, nitrated proteins, and the membrane lipid peroxidation product 4-hydroxynonenal (HNE) after exposure to the apoptotic insults were markedly attenuated in cells expressing MnSOD. Glutathione peroxidase activity levels were increased in cells overexpressing MnSOD, suggesting a compensatory response to increased H2O2 levels. The peroxynitrite scavenger uric acid and the antioxidants propyl gallate and glutathione prevented apoptosis induced by each apoptotic insult, suggesting central roles for peroxynitrite and membrane lipid peroxidation in oxidative stress-induced apoptosis. Apoptotic insults decreased mitochondrial transmembrane potential and energy charge in control cells but not in cells overexpressing MnSOD, and cyclosporin A and caspase inhibitors protected cells against apoptosis, demonstrating roles for mitochondrial alterations and caspase activation in the apoptotic process. Membrane lipid peroxidation, protein nitration, and neuronal death after focal cerebral ischemia were significantly reduced in transgenic mice overexpressing human MnSOD. The data suggest that mitochondrial superoxide accumulation and consequent peroxynitrite production and mitochondrial dysfunction play pivotal roles in neuronal apoptosis induced by diverse insults in cell culture and in vivo.

Animals↗

PubMed1998

Ischemic and excitotoxic brain injury is enhanced in mice lacking the p55 tumor necrosis factor receptor.

Ischemic and excitotoxic insults to the brain induce rapid production of tumor necrosis factor-alpha (TNF), but the role of TNF in neuronal responses to brain injury are unclear. Two different TNF receptors (p55 and p75) are expressed in neurons and glia. To understand the role of TNF in brain injury, we generated mice that lack p55, p75, or both receptors. We report that neuronal damage after focal cerebral ischemia-reperfusion is significantly increased in mice lacking p55 receptors (85+/-7 mm3 infarct volume; mean +/- SD) compared with wild-type mice (70+/-8 mm3) and mice lacking p75 receptors (72+/-6 mm3). Moreover, mice lacking p55 receptors exhibited increased degeneration of CA3 hippocampal neurons after administration of the excitotoxin kainic acid compared with wild-type mice and mice lacking p75 receptors. When taken together with recent data showing that TNF can prevent apoptosis of cultured neurons exposed to oxidative and metabolic insults, our findings suggest that TNF plays a neuroprotective role after acute brain insults.

Animals↗

PubMed1998

Reduction in amyloid A amyloid formation in apolipoprotein-E-deficient mice.

Apolipoproteins have been implicated in the formation of amyloid fibrils. Recent studies have demonstrated that apolipoprotein E (apoE), alone or in combination with apolipoprotein J (apoJ), and other lipoproteins appear to enhance deposition of amyloid fibrils both in systemic and cerebral amyloids, especially Alzheimer's disease (AD). ApoE enhanced the ability of the amyloid beta-protein (1-40) fragment (A beta) to form fibrils in vitro, with apoE4 promoting the greatest fibril formation. ApoE was found associated with both human and mouse amyloid A (AA) deposits. To define the role of apoE in vivo, we utilized mice lacking the apoE gene by gene targeting. We used the AA model in mice to characterize the function of the apoE protein in amyloid fibrillogenesis. ApoE-deficient mice exhibited a decrease in deposition of AA when compared with heterozygous mutant or wild-type animals. In addition, apoE-deficient mice that were injected with an adenovirus that expressed the human apoE3 gene had restored AA deposition and the apoE was associated with the AA fibrils. These results are agreement with the in vitro studies using the beta-peptide and suggest that apoE is not essential for amyloid fibrillogenesis but can promote the development of amyloid deposition.

Acute-Phase Proteins↗

PubMed1997

Beneficial effects of S-adenosyl-L-methionine on blood-brain barrier breakdown and neuronal survival after transient cerebral ischemia in gerbils.

We have studied the beneficial effects of S-adenosyl-L-methionine (SAM) tosylate on blood-brain barrier (BBB) breakdown and neuronal survival after transient cerebral ischemia in gerbils. BBB breakdown experiments were performed in pentobarbital anesthetized gerbils subjected to 10 min of bilateral carotid artery occlusion and 6 h of reperfusion. For BBB breakdown measurements, SAM (120 mg/kg, i.p.) was administered to gerbils just after occlusion and thereafter every hour up to 5 h. Fluorometric measurements quantified the blood-brain permeability tracer, Evans blue (EB). SAM treatment significantly reduced the BBB breakdown as indicated by reduced levels of EB fluorescence. Neuronal count experiments were conducted in gerbils subjected to transient ischemia and 7 days of reperfusion. For neuronal count experiments SAM (15-120 mg/kg) was administered at 6 and 12 h after reperfusion, and twice each day thereafter for 7 days. SAM dose dependently protected the hippocampal CA1 neurons assessed by histopathological methods. SAM has a beneficial effect on the outcome of ischemic injury by reducing the BBB breakdown and neuronal death.

Animals↗

PubMed1997

Adenoviral vector-mediated overexpression of serum amyloid A in apoA-I-deficient mice.

Serum amyloid A (SAA) is an acute phase reactant that can become the predominant apolipoprotein of high density lipoprotein (HDL) during severe inflammatory states. However, the function of SAA is unknown. To study the ability of SAA to form HDL in the absence of apolipoprotein A-I, we expressed the mouse SAA pI 6.15 (CE/J) isoform in apolipoprotein A-I knock-out (apoA-I (-/-)) mice using a recombinant adenovirus. As a control, apoA-I (-/-) mice were injected with an adenovirus expressing human apoA-I. High level expression of plasma SAA was obtained in the absence of any endogenous acute phase SAA production. SAA expression increased plasma HDL cholesterol levels about 2-fold, but to a lesser extent than the expression of apoA-I (about 10-fold). The HDL particles isolated by density ultracentrifugation from SAA-expressing mice were heterogeneous in size and composition and rich in free cholesterol as well as apoE and apoA-IV. Of the SAA expressed in the plasma, only a small fraction (4%) was associated with HDL particles in contrast to expressed apoA-I, of which 62% was associated with HDL. We conclude that SAA is unable to substitute for apoA-I in HDL particle formation.

Acute-Phase Reaction↗

PubMed1996

Inhibition of Alzheimer's amyloidosis by peptides that prevent beta-sheet conformation.

Amyloid beta-peptide (A beta) is a major fibrillar component of neuritic plaques in Alzheimer's disease (AD) brains and is related to the pathogenesis of the disease. We hypothesized that amyloid formation could be inhibited by peptides homologous to A beta (position 17-21) with a similar degree of hydrophobicity, but with a very low propensity to adopt a beta-sheet conformation by incorporating proline residues (anti-beta-sheet peptides or beta-sheet inhibitors). An 11-residue peptide with these characteristics binds to A beta, inhibits A beta fibril formation and partially disaggregates preformed fibrils in vitro. Shorter anti-beta-sheet peptides and analogs containing D-amino acids are also able to inhibit A beta fibrillogenesis. The latter are more resistant to proteolytic degradation and may serve as a starting point to design more efficient peptides derivatives to inhibit amyloidogenesis in vivo.

Alzheimer Disease↗

PubMed1996

Structure of the mouse Saa4 gene and its linkage to the serum amyloid A gene family.

The serum amyloid A (SAA) proteins are a polymorphic family of apolipoproteins associated with high-density lipoproteins (HDL). Three distinct subfamilies have been identified: (i) a cytokine-induced acute phase subfamily that is hepatically produced and can become the major apolipoprotein on HDL (SAA1, SAA2); (ii) a peripherally produced acute phase SAA3 that is only a minor HDL apolipoprotein; and (iii) a constitutive subfamily (SAA4) that is a minor normal HDL apolipoprotein comprising more than 90% of the SAA during homeostasis. Here we define the structure of the Saa4 gene. Similar to other Saa family members, it has four exons and three introns. It is 4588 bp long from the transcription start site to the end of the 3'-untranslated region and is approximately 20% larger than other Saa genes. We have located Saa4 11 kb upstream from Saa3 and 5 kb downstream from Saa1, with the pseudogene approximately 1 kb from the 5' end of Saa4. Saa4 has the same orientation as most other Saa family members, with only Saa2 having an opposing orientation. These data promote our understanding of the evolution of the Saa family. They enhance our ability to develop the mouse as a transgenic and gene deletion model to advance the understanding of the function of these apolipoproteins.

Animals↗

PubMed1996

Induction of PGH synthase and c-fos mRNA during early reperfusion of ischemic rat brain.

We examined the effect of reversible ischemia on the transcription of prostaglandin endoperoxide synthase (PGHS-1) and c-fos mRNA in rat cerebral cortex. The level of PGHS-1 mRNA climaxed after 30 min of ischemia whereas transcription of c-fos mRNA peaked after 60 min of postischemic reperfusion. We conclude that cerebral ischemia causes early transcription of PGHS-1, without modulation by the c-fos gene or its translated product.

Animals↗

PubMed1996

Altered neuronal and microglial responses to excitotoxic and ischemic brain injury in mice lacking TNF receptors.

Brain injury, as occurs in stroke or head trauma, induces a dramatic increase in levels of tumor necrosis factor-alpha (TNF), but its role in brain injury response is unknown. We generated mice genetically deficient in TNF receptors (TNFR-KO) to determine the role of TNF in brain cell injury responses. Damage to neurons caused by focal cerebral ischemia and epileptic seizures was exacerbated in TNFR-KO mice, indicating that TNF serves a neuroprotective function. Oxidative stress was increased and levels of an antioxidant enzyme reduced in brain cells of TNFR-KO mice, indicating that TNF protects neurons by stimulating antioxidant pathways. Injury-induced microglial activation was suppressed in TNFR-KO mice, demonstrating a key role for TNF in injury-induced immune response. Drugs that target TNF signaling pathways may prove beneficial in treating stroke and traumatic brain injury.

Animals↗

PubMed1995

Association of apolipoprotein E with murine amyloid A protein amyloid.

BACKGROUND: Experimental amyloid A protein (AA) amyloidosis in mice is the most rapid type of amyloid formed, thus providing a valuable model to study amyloid formation. Recent studies have suggested the importance of apolipoprotein E (apoE) in Alzheimer's disease and systemic amyloidoses. To help understand the role of apoE in amyloidoses, we examined amyloid tissue for the presence of apoE in mouse AA amyloid. EXPERIMENTAL DESIGN: Mice were injected with amyloid-enhancing factor and silver nitrate to induce amyloid deposition. Spleens were examined for Congo red staining and serum amyloid A, serum amyloid P component, and apoE immunostaining. In addition, RNA analysis was performed to measure the expression of apoE in various tissues after amyloid induction. RESULTS: We have found that apoE is associated with mouse amyloid. Ab to apoE consistently detected the presence of increased levels of apoE in amyloid tissue. Immunohistochemical analyses confirmed that the apoE immunoreactivity co-associated with AA and serum amyloid P in the amyloid fibrils. Northern blot analysis of amyloid tissue showed an increase in apoE messenger RNA compared with control tissue. CONCLUSIONS: This is the first demonstration of apoE in mouse amyloid tissue. The data presented here, along with previous studies, suggest that apoE may be involved in amyloidogenesis. These studies validate the mouse model for studying the role of apoE in amyloid fibrillogenesis. The use of transgenic and gene-inactivated mice will help to elucidate the role and mechanism of apoE in amyloid formation.

Amyloidosis↗

PubMed1995

Characterization of constitutive human serum amyloid A protein (SAA4) as an apolipoprotein.

Serum amyloid A proteins (SAAs), a family of homologous molecules, are apolipoproteins of high density lipoprotein (HDL). They can be divided into two groups. The first group comprises the well-characterized acute phase SAAs that associate with HDL during inflammation, thereby remodeling the HDL particle by displacing apolipoprotein (apo)A-I. The second group consists of the recently discovered constitutive SAAs, mouse SAA5 and human SAA4. They exist as minor apolipoproteins on HDL but constitute more than 90% of the total SAA during homeostasis. We have characterized human SAA4 as an apolipoprotein. During homeostasis, SAA4 is synthesized only in the liver. Purification of SAA4 has been described and its plasma concentration has been established at 55 +/- 13 micrograms/ml in 26 healthy individuals. It was present on all HDL density classes and very low density lipoprotein (VLDL) but was absent from low density lipoprotein (LDL). Using two-dimensional electrophoresis and phosphorimaging, SAA4 was found to be associated with a specific subpopulation of only three HDL particles, not involved in the initial cholesterol transfer from cells.

Acute-Phase Reaction↗

PubMed1994

Mouse serum amyloid A protein (SAA5) structure and expression.

A novel member of the mouse serum amyloid A protein family, SAA5, has been identified as a normal apolipoprotein component of non-acute-phase high density lipoprotein (HDL). The structure of SAA5 was derived from a clone isolated from a normal Balb/c liver cDNA library. The clone predicts a pre-SAA5 molecule of 130 residues from which an 18-residue leader peptide is cleaved. The mature molecule has an octapeptide insert spanning from position 70 to 77. Similar inserts are found in human C-SAA and, paradoxically, in acute-phase SAA molecules of a number of other species. There is 48% amino acid identity between apo-SAA5 and the other mouse SAA proteins and 57% identity between the human C-SAA and apo-SAA5. The SAA5 mRNA is three times larger than previously identified SAA mRNAs. Although SAA5 is constitutively expressed in the liver, it has a rapid albeit muted response to inflammatory stimuli. The increase of SAA5 mRNA is due to increased transcription rather than mRNA stabilization. Plasma SAA5 levels during the acute phase are biphasic, either because of translational control or displacement from HDL and rapid clearance. We propose that constitutive SAAs (SAA5) on normal HDL contribute to its normal physiological role, whereas the dramatically inducible family members (SAA1, SAA2, SAA3) equip this particle for an altered functional role during inflammation.

Amino Acid Sequence↗

PubMed1994

Blockade of ornithine decarboxylase enzyme protects against ischemic brain damage.

Polyamines are derived from ornithine by the actions of ornithine decarboxylase (ODC), which is the rate-limiting step in this pathway. Polyamines play a role in cell growth, neoplasia, differentiation, and response to injury. We have shown that transient cerebral ischemia gives rise to increased ODC mRNA and enzyme activity in the gerbil brain. ODC and polyamines are thought to be important in the generation of edema and the neuronal cell loss associated with cerebral ischemia. To test this theory, we examined the ODC activity, putrescine levels, and neuronal density in the CA1 region of the hippocampus following ischemia and reperfusion injury in the absence and presence of an inhibitor of ODC activity, alpha-difluoromethylornithine (DFMO). Pretreatment of animals with DFMO resulted in attenuation of the ODC activity following 5 min of ischemia and 4 h of reperfusion. In addition, DFMO prevented the increase in polyamine levels, as determined by measurement of putrescine in the ischemic brain. These alterations were not due to changes in ODC mRNA level. Further analysis revealed that DFMO treatment blocked the delayed neuronal cell death in the CA1 region of the hippocampus that accompanies ischemia and reperfusion injury. Administration of DFMO resulted in a dose-dependent beneficial effect upon neuronal cell survival. These results suggest that ODC enzyme activity and the production of polyamines play a significant role in the response of the brain to ischemic injury.

Animals↗

PubMed1993

Ontogeny of proenkephalin mRNA and enkephalin peptide expression in the cerebellar cortex of the rat: spatial and temporal patterns of expression follow maturational gradients in the external granular layer and in Purkinje cells.

Proenkephalin mRNA and peptide products were examined in developing cells of the postnatal rat cerebellar cortex using in situ hybridization and immunocytochemistry. On day 7, proenkephalin mRNA was first detected as discrete cellular labeling in Golgi cells and as a diffuse hybridization signal over the Purkinje cell layer. On day 14, proenkephalin mRNA and peptide products primarily appeared in distinct subpopulations of Purkinje cells present in the posterior and lateral cerebellum. Similarly, in the external granular layer (EGL), enkephalin immunoreactivity was present only in the posterior and lateral portions of the cerebellum on day 14. However, proenkephalin mRNA was not detected in enkephalin-immunoreactive EGL cells. On day 21, the subset of Purkinje cells that expressed proenkephalin mRNA and peptides were distributed more uniformly throughout the cerebellum. On day 28, a few enkephalin-immunoreactive Purkinje cells were uniformly present throughout the cerebellum, but proenkephalin mRNA was not detected in most of these cells. The spatial gradients in proenkephalin mRNA expression evident in the Purkinje cells of younger rats were no longer present in 28-day-old rats. These findings are important, because endogenous opioids such as enkephalin have been previously shown to inhibit the growth of Purkinje cell dendrites and dendritic spines, and inhibit the rate of mitosis in EGL neuroblasts. Cells do not develop at uniform rates within the cerebellum. There are regional differences in the timing of the formation of the EGL, and in the morphogenesis of Purkinje cells. In conjunction with previous work, the present findings suggest that during development, the pattern of enkephalin immunoreactivity in Purkinje and EGL cells closely follows the spatial and temporal gradients of maturation in both these cell types. The emergence and disappearance of enkephalin immunoreactivity in Purkinje and EGL cells is spatially and temporally related, and coincides with proenkephalin mRNA expression in Purkinje cells. Thus, the transient and coordinated appearance of enkephalin in cerebellar Purkinje and EGL cells may contribute to regional differences in the rate of cerebellar maturation, and may help synchronize the developmental interactions between these two cell types.

Animals↗

PubMed1993

Structural prerequisites for serum amyloid A fibril formation.

Most studies of experimental amyloid A protein (AA) amyloidosis in mice have been performed in type A mice with BALB/c as the prototype. In these mice the products of two genes, SAA1 and SAA2, are the major apo-SAA isoforms on high density lipoprotein (HDL). Of these two isoforms, that differ at nine amino acids, only apo-SAA2 is rapidly cleared and deposited as amyloid fibrils. No mouse strain has ever been shown to be completely resistant to amyloid induction. We have found the CE/J mouse strain to be exceedingly resistant to amyloidogenesis. Data indicate that this resistance is not due to a lack of apo-SAA synthesis but rather resides in the unique apo-SAA isoform in this strain. CE/J mice have a single major apo-SAA isoform (pI 6.15) the product of a single gene. This is a hybrid molecule with features of both apo-SAA1 and apo-SAA2, differing from the latter at only six amino acids. When CD studies were performed to explore the structural relationship of this isoform to apo-SAA1 and apo-SAA2, we found that when bound to heparan sulfate proteoglycan the CE/J pI 6.15 isoform fails to undergo the beta-sheet folding typical for apo-SAA2. This evidence suggests that the folding effect of heparan sulfate proteoglycan on apo-SAA2 is important in amyloid formation.

Amino Acid Sequence↗